Electronic devices provided with a substrate to which semiconductor elements are attached are conventionally known. FIG. 36 is a cross-sectional view showing a structure of an electronic device according to a conventional example, the electronic device provided with a substrate to which semiconductor elements are attached.
As shown in FIG. 36, the electronic device 2001 according to the conventional example has a plurality of semiconductor elements 2002, a substrate 2003 to which the plurality of semiconductor elements 2002 are attached, heat-dissipating sheets 2004 disposed over the semiconductor elements 2002, a metal plate 2005 that contacts the semiconductor elements 2002 via the heat-dissipating sheets 2004, and a chassis 2006 disposed a predetermined distance away from the substrate 2003.
The plurality of semiconductor elements 2002 include a semiconductor element 2002a and a semiconductor element 2002b having mutually different thicknesses. For example, the semiconductor element 2002b has a greater thickness than the semiconductor element 2002a. 
The plurality of heat-dissipating sheets 2004 include a heat-dissipating sheet 2004a disposed over the semiconductor element 2002a, and a heat-dissipating sheet 2004b disposed over the semiconductor element 2002b. 
A plurality of protruding parts 2005a and 2005b that protrude towards the substrate 2003 side are formed on the metal plate 2005. The plurality of protruding parts 2005a and 2005b are formed to have mutually different protruding heights, for example, the protruding part 2005b has a lesser protruding height than the protruding part 2005a. 
Moreover, the protruding part 2005a is formed at a position in opposition to the semiconductor element 2002a, while the protruding part 2005b is formed at a position in opposition to the semiconductor element 2002b. The semiconductor element 2002a contacts the protruding part 2005a via the heat-dissipating sheet 2004a, and the semiconductor element 2002b contacts the protruding part 2005b via the heat-dissipating sheet 2004b. By so doing, it is possible for the heat generated by the semiconductor elements 2002 to be dissipated to the metal plate 2005.
The substrate 2003 and the metal plate 2005 are fixed to the chassis 2006 by fixing members (not shown).
Structures for dissipating heat generated by semiconductor elements into a metal plate are disclosed, for example, in Patent Literature 1 and Patent Literature 2.